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Power quality problems are becoming a major issue. Every utility company consumer desires to receive steady-state voltage, i.e. a sinusoidal waveform of constant frequency as generated at power stations, but the influence of disturbances in the shape of sags and swells, interruptions, transients and harmonic distortions which affect power quality, resulting in loss of data, damaged equipment, and augmented cost. The most powerful voltage disturbance is the sag voltage. In this paper, a Dynamic Voltage Restorer (DVR) is proposed for sag voltage compensation. It is cost-effective and protects critical loads in a good manner from balanced or unbalanced sag voltage. Control strategy (such as a PI controller) is adopted with DVR topology and the performance of such a device with the proposed controller is analyzed through simulation in MATLAB/Simulink. Three types of faults are utilized, which are available in MATLAB/Simulink pack, for obtaining the sag voltage. The specific range of total harmonic distortion percentage is also discussed. After the result validation of the DVR topology in MATLAB/Simulink, it has been seen that the proposed topology is able to compensate the sag voltage of any type of fault and reduce the unbalancing and voltage distortions of the grid.

Renewable power generation sources used as distributed generations (DGs) are increasing rapidly all around the world. Apart from environmental advantages, DGs result in reduction of power losses, improvement of bus voltages, increased system reliability, stability, power quality and ease of operation. In this work, the impacts of DG on power losses, bus voltages and short circuit level of the power system are investigated with different case strategies of DG interconnections. With every strategic case, the DG impacts on power system are analyzed by network simulation through Power System Simulator Siemens Network Calculator software (PSS SINCAL). Significant power losses and voltage improvement were observed depending on size and strategic locations of DG interconnections. Slight increase in network short circuit levels is observed within permissible limits of protection devices. The communication prospects of DG and Smart Grid Integration are also discussed to enable the monitoring, control of interconnected DG units with a two-way electricity and information flow to develop an automated distributed energy network. Finally, an attempt is made to strategize a simple and gradually applicable model of controlling the network conditions through the integration of DGs. Using the state of art of DG integration models, the gradually implementable smart grid system is proposed for under developed countries, like Pakistan.

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